Multi-layer gas barrier materials for vacuum insulated structure

ABSTRACT

A vacuum insulated structure includes a multi-layer sheet of material comprising at least one layer of barrier material that is disposed between first and second outer layers. The barrier material and the first and second outer layers comprise thermoplastic polymers or elastomeric or hybrid material systems. The multi-layer sheet of material is thermoformed or vacuum formed to form a non-planar first component having a central portion and four sidewalls extending transversely from the central portion. A second component having a central portion and four sidewalls extending transversely from the central portion is secured to the first component to form an interior space therebetween. Porous filler material is positioned in the interior space, and a vacuum is formed in the interior space by removing gasses and moisture (water vapor). The first and second components are sealed together to form a vacuum insulated structure.

The present application is a Continuation of U.S. patent applicationSer. No. 14/980,778 entitled “MULTI-LAYER GAS BARRIER MATERIALS FORVACUUM INSULATED STRUCTURE,” filed Dec. 28, 2015, which is herebyincorporated by reference.

BACKGROUND OF THE INVENTION Background of the Invention

Various types of vacuum panels and other vacuum insulated structureshave been developed for use in refrigerator cabinets, doors, cookingcavities (ovens), dryer systems, water heaters, freezers, insulationboxes and pipe systems and other such components. Vacuum insulatedstructures may have superior insulation properties relative toconventional polyurethane foam insulation. However, known vacuuminsulated structures and processes for fabricating such structures maysuffer from various drawbacks.

SUMMARY OF THE INVENTION

A vacuum insulated structure includes a multi-layer sheet of materialcomprising at least one layer of barrier material that is disposedbetween first and second outer layers. The barrier material and thefirst and second outer layers comprise thermoplastic polymers orelastomeric or hybrid material systems. The multi-layer sheet ofmaterial is thermoformed or vacuum formed to form a non-planar firstcomponent having a central portion and four sidewalls extendingtransversely from the central portion. A second component having acentral portion and four sidewalls extending transversely from thecentral portion is secured to the first component to form an interiorspace therebetween. Porous filler material is positioned in the interiorspace, and a vacuum is formed in the interior space. The first andsecond components are sealed together to form a vacuum insulatedstructure.

These and other features, advantages, and objects of the presentinvention will be further understood and appreciated by those skilled inthe art by reference to the following specification, claims, andappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a refrigerator;

FIG. 2 is an exploded isometric view of a refrigerator cabinet;

FIG. 3 is an exploded isometric view of a vacuum insulated doorstructure for a refrigerator;

FIG. 4 is partially schematic cross sectional view of a multilayermaterial that may be utilized to form wrappers, liners, and other suchcomponents of refrigerator cabinets, doors, and the like;

FIG. 5 is a partially schematic exploded cross sectional view of athree-layer sheet of material;

FIG. 6 is a partially schematic exploded cross sectional view of afour-layer sheet of material;

FIG. 7 is a schematic view of a thermoforming tool/process; and

FIG. 8 is a schematic view of a thermoforming tool/process.

DETAILED DESCRIPTION

For purposes of description herein, the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” and derivativesthereof shall relate to the device as oriented in FIG. 1. However, it isto be understood that the invention may assume various alternativeorientations and step sequences, except where expressly specified to thecontrary. It is also to be understood that the specific devices andprocesses illustrated in the attached drawings, and described in thefollowing specification, are simply exemplary embodiments of theinventive concepts defined in the appended claims. Hence, specificdimensions and other physical characteristics relating to theembodiments disclosed herein are not to be considered as limiting,unless the claims expressly state otherwise.

With reference to FIG. 1, a refrigerator 1 includes an insulated cabinet2 having an upper fresh food compartment 6 that can be accessed throughaccess opening 7 by opening doors 4A and 4B. The insulated refrigeratorcabinet 2 also includes an insulated freezer compartment 8 that can beaccessed through access opening 9 by opening a lower door/drawer 4C.Refrigerator 1 may include a cooling system (not shown) disposed in amachine compartment 10. The cooling system may include a compressor,condenser, evaporator, and other related components that are generallyknown in the art. Alternatively, the cooling system may comprise one ormore thermoelectric elements. Door 4A may include an ice/water dispenser16.

With further reference to FIG. 2, refrigerator cabinet 2 may comprise awrapper 18 and a liner 20 that fits inside the wrapper 18 whenassembled. An optional trim piece 22 may be utilized to interconnect andseal off front edges 24 and 26 of wrapper 18 and liner 20, respectively,when cabinet 2 is assembled. As discussed in more detail below, wrapper18, liner 20, and/or trim piece 22 may be formed from a multilayerthermoplastic polymer material including one or more barrier layers thatare substantially impervious to nitrogen, oxygen, water vapor, carbondioxide, and other such gasses whereby a vacuum can be maintained in aninternal space between wrapper 18 and liner 20. The trim piece maycomprise thermosetting polymer material with or without fillers orreinforcements (e.g. fibers) and may optionally include a barriercoating. One or more of the components 18, 20 and 22 may optionally bemade from metal or other suitable material. For example, wrapper 18 maybe made from sheet metal, and liner 20 may be made from a multi-layerthermoformed polymer material having gas barrier properties. Wrapper 18may include a generally planar central sidewall portion 17, and foursidewalls 19A-19D that extend transversely from the central sidewallportion 17 to define an interior space 15 that receives liner 20 whenassembled. Liner 20 may include a generally planar rectangular centralsidewall 21 that is spaced from central sidewall 17 of wrapper 18 whenassembled. The liner 20 also includes sidewalls 23A-23D that extendtransversely from the central sidewall 21. When assembled, the sidewalls23A-23D are spaced inwardly from the sidewalls 19A-19D, respectively, ofwrapper 18 to form a gap or space therebetween that may be filled with aporous filler material and evacuated to form a vacuum.

With further reference to FIG. 3, a refrigerator door 4A-4C may includean outer panel member 18A, and an inner liner 20A. The outer panelmember 18A and liner 20A may be formed from a multilayer thermoformedpolymer material having barrier properties as discussed below to therebypermit forming a vacuum between outer member 18A and liner 20A whenassembled. The outer door member 18A may, alternatively, be formed fromsheet metal or other material. Outer member 18A may include flanges32A-32D that fit over and overlap corresponding flanges 34A-34B of liner20A when assembled. The liner 20A may optionally include one or moreraised ribs 28A-28C and shelves 30 as may be required for a particularapplication.

With reference to FIG. 4, a vacuum insulated refrigerator structure 40includes a multi-layer polymer wrapper 42 and a multi-layer polymerliner 44. Wrapper 42 and/or liner 44 may comprise thermoformed tri-layerpolymer material 60 (FIG. 5) or thermoformed quad-layer polymer material70 (FIG. 6). Vacuum insulated structure 40 may comprise a vacuuminsulated cabinet structure 2, a vacuum insulated door 4A-4C, or othervacuum insulated refrigerator structure. Polymer wrapper 42 may includeflanges 46 that overlap flanges 48 of polymer liner 44. The flanges 46and 48 may be interconnected to form an airtight seal. Alternatively,the polymer wrapper 42 and polymer liner 44 may be interconnectedutilizing other suitable connecting structures and techniques such asadhesive joining, welding, or a compression fitting gasket joint. Thepolymer wrapper 42 and polymer liner 44 form an interior space 50 thatmay be filled with a porous filler material 52 such as nano or microporous insulating material such as fumed silica, precipitated silica,hollow glass microsphere, perlite, rice husk ash, ceno sphere or flyash, and the interior space 50 may be evacuated and sealed whereby theinterior space 50 defines a vacuum. During fabrication, the polymerwrapper 42 and polymer liner 44 may be assembled together and sealinglyinterconnected. The wrapper and liner 42 and 44 may then be placed in avacuum chamber, and nano or micro porous insulation material 52 such asfumed silica, precipitated silica, hollow glass microsphere, perlite,rice husk ash, cenosphere or fly ash may be introduced into the interiorspace 50 through one or more openings 54. The openings 54 may then besealed with a barrier cap 56, and the vacuum insulated refrigeratorstructure 40 may then be removed from the vacuum chamber.

With further reference to FIG. 5, the wrapper 42 and/or liner 44 may bethermoformed from a tri-layer sheet 60 of polymer material. The sheet 60comprises first and second outer structural layers 62 and 64 and abarrier layer 66 that is disposed between the first and second outerstructural layers 62 and 64, respectively. The layers 62, 64, and 66comprise thermoplastic polymers or elastomeric material which may bethermoformed utilizing various processes as discussed below inconnection with FIGS. 7 and 8. Layers 62, 64, and 66 are shown in aspaced apart exploded view in FIG. 5. However, it will be understoodthat the layers 62, 64, and 66 are coextruded or laminated together toform a single multi-layer sheet prior to thermoforming. The first andsecond outer layers 62 and 64, respectively, may comprise a suitablethermoplastic polymer material such as High Impact Polystyrene (HIPS) orAcrylonitrile, Butadiene and Styrene (ABS), Polypropylene or PolyButylene Teraphthalate or Polyethylene. The barrier layer 66 maycomprise a thermoplastic polymer or elastomeric material that isimpervious to one or more gasses such as nitrogen, oxygen, water vapor,carbon dioxide, etc. such that the wrapper and liner 42 and 44 (FIG. 4)provide a barrier to permit forming a vacuum in interior space 50. Thebarrier layer 66 preferably comprises a material that blocks both oxygenand water vapor simultaneously. Examples of such material includePolyvinylidene Chloride (PVdC), nylon, or liquid crystal polymer. Thelayers 62, 64, and 66 may be co-extruded or laminated together. Thethickness of the barrier layer 66 may be adjusted as required fordifferent applications to meet varied requirements with respect tooxygen and water vapor transmission rates. The materials of layers 62,64, and 66 are selected to have very good thermoforming properties topermit deep draw ratio thermoforming of components such as wrapper 18and liner 20 (FIG. 2) and the door components 18A and 20A (FIG. 3), andother vacuum insulated refrigerator structures. Typically, the firstouter layer 62, and the second outer layer 64 has a thickness of about0.1 mm to 10 mm, and the barrier layer has a thickness of about 0.1 mmto 10 mm.

The following are examples of material combinations that may be utilizedto form tri-layer sheet 60:

Example 1: HIPS/PVdC/HIPS Example 2: HIPS/Nylon/HIPS Example 3:HIPS/MXD-6 Nylon/HIPS

Example 4: HIPS/MXD-6 Nylon with clay filler/HIPS

Example 5: HIPS/Liquid Crystal Polymer/HIPS

With further reference to FIG. 6, a quad-layer sheet 70 having first andsecond outer layers 72 and 74, respectively, and two barrier layers 76and 78 may also be utilized to form wrapper 18, liner 20 (FIG. 2) andouter member 18A and inner member 20A (FIG. 3) to form vacuum insulatedrefrigerator cabinet structures, vacuum insulated doors, or cookingcavities (e.g. ovens), dryer systems, water heaters, freezers,insulation boxes and pipe systems other such components. The outerstructural layers 72 and 74 may comprise HIPS, ABS, or other suitablepolymer material that is capable of being thermoformed. The firstbarrier layer 76 may comprise a thermoplastic polymer material that issubstantially impervious to water vapor. Examples of thermoplasticpolymer or elastomeric materials for first barrier layer 76 includefluoropolymer such as Tetrafluoroethylene (THV),polychlorotrifluoroethylene (PCTFE), Cyclic Olefin Copolymer (COC),Cyclic Olefin Polymer (COP) or high density polyethylene (HDPE). Thesecond barrier layer 78 may comprise a thermoplastic polymer that issubstantially impervious to oxygen. Examples of thermoplastic polymermaterials include Ethylene vinyl alcohol (EVOH). An optional tie layer80 comprising a thermoplastic polymer material may be disposed betweenthe barrier layers 76 and 78. Tie layer 80 may be utilized to bondbarrier layers 76 and 78 to one another. Examples of suitable materialsfor the tie layer include adhesive resins, such as modified polyolefinwith functional groups that are capable of bonding to a variety ofpolymers and metals.

The following are examples of material combinations that may be utilizedto form quad-layer sheet 70:

Example 1: HIPS/EVOH/HDPE/HIPS Example 2: HIPS/EVOH/COP/HIPS Example 3:HIPS/EVOH/COC/HIPS Example 4: HIPS/EVOH/THV/HIPS Example 5:HIPS/EVOH/PCTFE/HIPS

Layers 72, 74, 76, 78 and 80 are coextruded or laminated together toform a single sheet of material prior to thermoforming.

With further reference to FIGS. 7 and 8, multi-layer sheets 60 and 70may be thermoformed utilizing male and female mold parts 86 and 88,respectively. Sheet 60 or 70 is initially positioned between mold parts86 and 88 as shown in FIG. 7, and the sheet 60 or 70 is heated totemperature at which the sheet 60 or 70 can be plastically deformed bypressing the mold parts together as shown in FIG. 8 to form a wrapper,liner, or other such component. As used herein, the term “thermoforming”and variations thereof broadly means a forming process in which a sheetof thermoplastic polymer material is heated and formed, and“thermoforming” is not limited to the specific process/tools shown inFIGS. 7 and 8. For example, components may be thermoformed utilizing avacuum forming process whereby a vacuum is utilized to deform sheet 60or 70 to fit closely in female mold 87 such that a male mold part 86 isnot required.

It will be understood that wrappers, liners, and other such componentsas disclosed herein are not limited to the tri-layer sheet 60 or thequad-layer sheet 70 configurations described above, and additionallayers of material may also be utilized.

It is to be understood that variations and modifications can be made onthe aforementioned structure without departing from the concepts of thepresent disclosure, and further it is to be understood that suchconcepts are intended to be covered by the following claims unless theseclaims by their language expressly state otherwise.

The invention claimed is:
 1. A vacuum insulated appliance structure,comprising: a non-planar first component having a central portion andfour sidewalls extending transversely from the central portion, whereinthe non-planar first component is formed from a multi-layer sheet ofmaterial comprising at least one layer of barrier material disposedbetween first and second outer layers, wherein the barrier material andthe first and second outer layers comprise thermoplastic polymers and/orelastomeric material; a second component having a central portion andfour sidewalls extending transversely from the central portion, whereinthe second component is secured to the first component to form anairtight sealed interior space therebetween; porous filler materialdisposed in the airtight sealed interior space; and wherein the interiorspace is substantially evacuated of gasses to form a vacuum around theporous filler material.
 2. The vacuum insulated appliance structure ofclaim 1, wherein: the first component comprises a wrapper of arefrigerator cabinet; the second component comprises a liner of arefrigerator cabinet that is received inside the wrapper.
 3. The vacuuminsulated appliance structure of claim 1, wherein: the second componentcomprises a metal liner of a refrigerator cabinet.
 4. The vacuuminsulated appliance structure of claim 1, wherein: the outer layerscomprise at least one of HIPS or ABS, PP, PBT and PE.
 5. The vacuuminsulated appliance structure of claim 4, wherein: the barrier materialcomprises at least one of PVdC, nylon, and liquid crystal polymer. 6.The vacuum insulated appliance structure of claim 4, wherein: the atleast one layer of barrier material comprises first and second barrierlayers comprising first and second barrier materials, respectively,wherein the first barrier material is impervious to water vapor, and thesecond barrier material is impervious to oxygen.
 7. The vacuum insulatedappliance structure of claim 6, wherein: the first barrier materialcomprises at least one of a fluoropolymer, COC, COP, and HDPE.
 8. Thevacuum insulated appliance structure of claim 6, wherein: the secondbarrier material comprises EVOH.
 9. The vacuum insulated appliancestructure of claim 6, including: a tie layer disposed between the firstand second barrier layers, wherein the tie layer comprises a tyingpolymer material that bonds to the first and second barrier materials.10. The vacuum insulated appliance structure of claim 9, wherein: thetie layer polymer material comprises modified polyolefin with functionalgroups whereby the tie layer polymer is capable of bonding to polymersand metals.
 11. The vacuum insulated appliance structure of claim 1,wherein: the four transversely-extending sidewalls are formed bythermoforming the multi-layer sheet of material.
 12. A vacuum insulatedstructure, comprising: a first component having a central portion and aplurality of sidewalls extending transversely from the central portion,wherein the first component is formed from a multi-layer sheet ofmaterial comprising at least one layer of barrier material disposedbetween first and second outer layers, wherein the barrier material andthe first and second outer layers comprise thermoplastic polymers and/orelastomeric material; a second component sealed to the first componentto form an airtight interior space therebetween, wherein the secondcomponent includes a central portion and a plurality of sidewallsextending transversely from the central portion; porous filler materialin the interior space; and wherein the interior space is substantiallyevacuated of gasses to form a vacuum.
 13. The vacuum insulated structureof claim 12, wherein: the transversely-extending sidewalls are formedfrom the multi-layer sheet of material heating and forming themulti-layer sheet of material.
 14. The vacuum insulated structure ofclaim 12, wherein: the first component comprises a wrapper of arefrigerator cabinet; the second layer component comprises a liner of arefrigerator cabinet that is received inside the wrapper.
 15. The vacuuminsulated structure of claim 12, wherein: the second component comprisesa metal liner of a refrigerator cabinet.
 16. The vacuum insulatedstructure of claim 12, wherein: the outer layers comprise at least oneof HIPS or ABS, PP, PBT and PE.
 17. The vacuum insulated structure ofclaim 16, wherein: the barrier material comprises at least one of PVdC,nylon, and liquid crystal polymer.
 18. The vacuum insulated structure ofclaim 16, wherein the at least one layer of barrier material comprisesfirst and second barrier layers comprising first and second barriermaterials, respectively, wherein the first barrier material isimpervious to water vapor, and the second barrier material is imperviousto oxygen.
 19. The vacuum insulated structure of claim 18, wherein: thefirst barrier material comprises at least one of a fluoropolymer, COC,COP, and HDPE.